In recent years, there has been a demand for increase in recording density and reduction in the seek time required for data recording/reading with the increase in recording volume of recording medium in the information recording/reading apparatuses such as a hard disk device, optical disk device and the like. For this reason, there has been a demand for increase in precision for higher recording density and higher speed for reducing seek time in the field of the information recording/reading head of the information recording/reading apparatus (herein after referred to as head driving device) as well.
As a result, it has been proposed that a friction drive actuator which uses a piezoelectric element which is a type of electromechanical conversion element is employed as the actuator of the head driving device in order to obtain both high precision and high speed. For example, a head driving device which includes two driving methods has been proposed. The driving methods are the high speed driving method (hereinafter referred to as resonant drive method) using resonance of the piezoelectric element, the method in which the displacement amount is large (about a few μm) and the high precision driving method (hereinafter referred to as expansion and contraction drive method) using expansion and contraction of the piezoelectric element, the method in which displacement amount is small (about a few nm) (see Unexamined Japanese Patent Application Publication No. 2001-222869 for example). Similarly, as an actuator drive method with high speed and high accuracy, there has been proposed a method in which the head is rapidly driven to the vicinity of a target position by resonant drive method and then is accurately positioned by expansion and contraction drive method (see Unexamined Japanese Patent Application Publication No. 2004-274837 for example).
However, as shown in FIG. 12, in resonant drive method, even if resonant drive ends at timing T1, some vibration remains for a while in the actuator after that, and this attenuates with time T. Thus in the methods of Unexamined Japanese Patent Application Publication No. 2001-222869 and Unexamined Japanese Patent Application Publication No. 2004-274837, there is a problem as follows. When the friction drive actuator is subjected to the expansion and contraction drive in a state where the vibration like the vibration after Timing T1 in FIG. 12 remains, minute displacement in the expansion and contraction drive is affected by the residual vibration, and accurate positioning can not be achieved.